1. Technical Field
The embodiments described herein relate to a semiconductor apparatus, and more particularly, to a data output is driving circuit for a semiconductor apparatus.
2. Related Art
FIG. 1 is block diagram illustrating a conventional data output driving circuit for a semiconductor apparatus according to one embodiment. As can be seen, FIG. 1 includes a driver block 10, a multiplexer 20 and a controller 30.
The multiplexer 20 is configured to receive clock signals ‘RCLKDO’ and ‘FCLKDO’ and 2 bit parallel data ‘RDO’ and ‘FDO’ and to output 1 bit serial data ‘UPDO’ and ‘DNDO’.
The controller 30 is configured to receive a code signal ‘EMRS’ output from an extended mode register set (EMRS) to determine a driver strength, i.e., an impedance, an on-die termination enable signal ‘ODTEN’ and a driver off signal ‘DOFF’ and to output driver select signals ‘PU<0:3>’ and ‘PD<0:3>’.
The driver block 10 includes a pull-up driver block 11 and a pull-down driver block 12.
FIG. 2 is a circuit diagram of the pull-up driver block of FIG. 1. As can be seen, the pull-up driver block 11 has four pull-up drivers PU60Ω, PU120Ω, PU240Ω and PU240Ω. Each of the pull-up drivers PU60Ω, PU120Ω, PU240Ω and PU240Ω is composed of a pre-driver PDRV and a main driver MDRV.
The pre-driver PDRV of the pull-up driver PU60Ω receives a one bit serial data ‘UPDO’, a driver select signal ‘PU<3>’ and on-die termination codes ‘PCODE<0:5>’, and outputs control codes ‘UPCODE3<0:5>’. The main driver MDRV of the pull-up driver PU60Ω has a plurality of transistors of which the sources are connected with power terminals and the gates receive the control codes ‘UPCODE3<0:5>’, and a plurality of resistors. One end of each of the resistors is connected with the drains of the plurality of transistors and the other end of each of the resistors is connected with one another.
The basic configurations of the pull-up drivers PU120Ω, PU240Ω and PU240Ω are the same as the pull-up driver PU60Ω. In this regard, if the impedances of the pull-up drivers are different from one another, the pull-up drivers are configured such that the transistors and the resistors constituting the main drivers thereof have different widths and resistances. The resistances of the resistors constituting a main driver MDRV increase in proportion to an impedance, and the widths of the transistors constituting the main driver MDRV decrease in inverse proportion to the impedance.
That is to say, referring to FIG. 2, when compared to the pull-up driver PU60Ω, the pull-up driver PU120Ω is configured such that the resistances of the resistors thereof increase two times and the widths of the transistors thereof decrease to one half. Also, when compared to the pull-up driver PU120Ω, the pull-up driver PU240Ω is configured such that the resistances of the resistors thereof increase two times and the widths of the transistors thereof decrease to one half.
The transistor WP has a basic width, the transistor WP/8 has a width corresponding to ⅛ of the width of the transistor WP, and the transistor WP*16 has a width corresponding to 16 times of the width of the transistor WP. In addition, the resistor RP has a basic resistance and the resistor RP*128 has a resistance corresponding to 128 times of the resistance of the resistor RP.
FIG. 3 is a circuit diagram of the pull-down driver block of FIG. 1 and the pull-down driver block 12 has four pull-down drivers PD60Ω, PD120Ω, PD240Ω and PD240Ω. Each of the pull-down drivers PD60Ω, PD120Ω, PD240Ω and PD240Ω is composed of a pre-driver PDRV and a main driver MDRV.
The pre-driver PDRV of the pull-down driver PD60Ω receives a one bit serial data ‘DNDO’, a driver select signal ‘PD<3>’ and on-die termination codes ‘NCODE<0:5>’, and outputs control codes ‘DNCODE3<0:5>’. The main driver MDRV of the pull-down driver PD60Ω has a plurality of transistors of which the sources are connected with ground terminals and the gates receive the control codes ‘DNCODE3<0:5>’ and a plurality of resistors of which one ends are connected with the drains of the plurality of transistors and the other ends are connected with one another.
The basic configurations of the pull-down drivers PD120Ω, PD240Ω and PD240Ω are the same as the pull-down driver PD60Ω. In this regard, if the impedances of the pull-down drivers are different from one another, the pull-down drivers are configured such that the transistors and the resistors constituting the main drivers thereof have different widths and resistances. The principle for configuring these pull-down drivers is the same as that for configuring the pull-up drivers shown in FIG. 2. The transistor WN has a basic width, the transistor WN/8 has a width corresponding to ⅛ of the width of the transistor WN, and the transistor WN*16 has a width corresponding to 16 times of the width of the transistor WN. In addition, the resistor RN has a basic resistance and the resistor RN*128 has a resistance corresponding to 128 times of the resistance of the resistor RN.
The operation of the conventional data output driving circuit of a semiconductor apparatus, configured as described above, will be described below.
The multiplexer 20 converts the 2 bit parallel data ‘RDO’ and ‘FDO’ into the 1 bit serial data ‘UPDO’ and ‘DNDO’ in response to the clock signals ‘RCLKDO’ and ‘FCLKDO’ and outputs the converted data.
The code signal ‘EMRS’ for determining the strength of the driver block 10 is output from the extended mode register set (EMRS).
The controller 30 determines the operation mode of the driver block 10 based on the on-die termination enable signal ‘ODTEN’ and the driver off signal ‘DOFF’, and outputs the driver select signals ‘PU<0:3>’ and ‘PD<0:3>’ to conform to the determined operation mode.
When data input operation is implemented in a semiconductor apparatus, the driver off signal ‘DOFF’ is deactivated, and the on-die termination enable signal ‘ODTEN’ is activated. According to this, the controller 30 activates only the driver select signals ‘PU<0:3>’ between the driver select signals ‘PU<0:3>’ and ‘PD<0:3>’ such that on-die termination operation can be implemented through the driver block 10, and thereby allows only the pull-up driver block 11 of the driver block 10 to operate.
In the driver block 10, an on-die termination strength, that is, an impedance is determined in response to the on-die termination codes ‘PCODE<0:5>’ and ‘NCODE<0:5>’.
When data output operation is implemented in the semiconductor apparatus, both the driver off signal ‘DOFF’ and the on-die termination enable signal ‘ODTEN’ are deactivated. According to this, the controller 30 activates all the driver select signals ‘PU<0:3>’ and ‘PD<0:3>’ such that the data output operation can be implemented through the driver block 10, and thereby allows both the pull-up driver block 11 and the pull-down driver block 12 of the driver block 10 to operate.
In the driver block 10, the strengths, that is, the driving impedances of the pull-up driver block 11 and the pull-down driver block 12 are determined in response to the driver select signals ‘PU<0:3>’ and ‘PD<0:3>’ output from the controller 30. The driver block 10 drives and outputs the data ‘UPDO’ and ‘DNDO’ with the determined impedances.
For example, in order to obtain the strength of 30Ω, all the pull-up drivers PU60Ω, PU120Ω, PU240Ω and PU240Ω are enabled. If all the pull-up drivers PU60Ω, PU120Ω, PU240Ω and PU240Ω are enabled, according to the parallel connection principle of resistors, the strength is calculated as 1/(1/60+1/120+1/240+1/240)=240/8=30Ω.
In addition, in order to obtain the strength of 40Ω, the pull-up drivers PU60Ω and PU120Ω are enabled among the pull-up drivers PU60Ω, PU120Ω, PU240Ω and PU240Ω. If the pull-up drivers PU60Ω and PU120Ω are enabled, according to the parallel connection principle of resistors, the strength is calculated as 1/(1/60+1/120)=120/3=40Ω.
When data input and output operations are not implemented in the semiconductor apparatus, the driver off signal ‘DOFF’ is activated, and the on-die termination enable signal ‘ODTEN’ is inactivated. According to this, the controller 30 inactivates all the driver select signals ‘PU<0:3>’ and ‘PD<0:3>’ such that both the pull-up driver block 11 and the pull-down driver block 12 of the driver block 10 do not operate.
As can be readily understood from the above description, the conventional data output driving circuit of a semiconductor apparatus has the plurality of drivers so as to obtain various driver strengths and on-die termination strengths. Specifically, in the case of the 120Ω and 240Ω drivers, since they occupy larger areas than the 60Ω driver, the area occupied by the data output driving circuit increases in the entire area of the semiconductor apparatus, whereby a layout margin decreases.